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Topic Review (Newest First)

12-19-2012 06:07 PM

ssmonty

Just thought I'd mention that you don't want to use a steel shim gasket with aluminum heads. Ask around.
ssmonty

12-19-2012 05:26 PM

BuzzLOL

.. You can also use the Edelbrock Performer RPM heads with 64cc chambers #60899 instead of the 70cc 60739's as a starting point... chamber size is a case where bigger usually isn't better... I don't think they offer a 58cc version for Chevy's...

12-19-2012 02:47 PM

techinspector1

Before you do anything, measure the piston deck clearance so I can compute your SCR. Here's how with cheap tools. All you need is a 6" or 12" steel rule and a set of feeler gauges. Bring any piston up to top dead center, stand the rule on edge about 1/4" from the edge of the bore at the 3 O'clock or 9 O'clock position as you are standing at the side of the short block. Trying to find the piston deck height with the steel rule placed at Noon or 6 O'clock will allow the piston to rock back and forth on its wrist pin and will give you false information. Stack feeler gauge blades together until you get a snug fit between the piston crown and the bottom of the rule. Hold the rule down firmly to the block deck, making absolutely certain that there is no air gap between the block deck and the bottom of the rule. Have a helper rock the crank back and forth a little clockwise and counter-clockwise to insure that the piston is at exact top dead center. Measure, re-measure and re-re-measure. I would do this on each corner of the deck, in other words on cylinders 1, 2, 7 and 8. In this way, you'll be able to find any discrepancy in the piston deck height, meaning that either the block needs to by cut to make the block decks parallel with the main bearing bore or one or more of the stack of parts (cylinder to cylinder) are not the same height. If the block decks are skewed (uphill/downhill) or not the same cylinder to cylinder, then the static compression ratio will be different from cylinder to cylinder. If you end up with an "on the edge" build with one or more cylinders making more cylinder pressure than the others, you could have detonation on those one or two cylinders while the rest of the cylinders are singing along happily. It's even possible that some of the pistons are 1.560" and some of them are 1.540". You have no idea until you measure the piston deck height as outlined above. With this simple procedure, you'll probably find that the corner to corner dimensions are off enough to make a problem. You can, of course, put the motor together without knowing any of this and it will run, but if you want the best performance from your build, you have to jump through some hoops.

My standard operating procedure includes align-honing or align-boring the main bearing bore, cutting the block decks to parallel with the main bearing bore, with the height of the deck being dependant on the stack of parts being used, along with the gasket dimensions and chamber volumes, then boring and honing the cylinders for new pistons that will work with my combination using torque plates, followed by a trial assembly where everything is measured before final assembly. That's how I do it. You can do it any way you wish or you can buy a crate motor and forget it.

12-19-2012 01:57 PM

BuzzLOL

.. Could also have the Performer RPM heads milled down to 58cc locally... then they would make a better match for an XE268 cam... call Eddy and ask them if that's possible... I think it is...

12-19-2012 01:11 PM

txdude350

MY very first post had all of that, except I guess I may need to go with a 58cc head.

12-19-2012 07:20 AM

vinniekq2

post your complete wish list.including head choice

12-19-2012 05:56 AM

txdude350

Thanks everyone... Does everyone agree that 9:1 is enough CR? I am not going to be running it at a track or anything, but speed is still important to me of course!!

12-18-2012 08:04 PM

632Mantis

I'm a big fan of the Edelbrock Performer RPM AIR GAP intake manifolds.
They truly are the best of both worlds, but you need hood clearance to run them. They are tall.

9:1 CR is fine for a pump gas street motor.
It's nice to zero-deck the block. Looks like you are running some smog-dog pistons.
If you have to run those pistons, get some heads with smaller chambers.
I'm thinking 58cc-62cc.

Comp Cams Xtreme Energy cams rock. Good choice.

12-18-2012 08:00 PM

BuzzLOL

.. That Lunati 230/230 @ .050" lift cam is an old grind and way too big for your possible compression ratios... it really needs about 11.0-11.5:1 to run properly... even then it wouldn't pull hard till above 3,000 RPMs... and with your compression ratios it would be like a vacuum leak and the engine would be a real dog at most street RPMs... and pisspoor MPG...

.. If you don't want to change pistons, I'd suggest looking around for a used pair of Chevy 350" Corvette/ZZX Crate engine -113 aluminum heads with 58cc chambers to keep compression ratio up into at least the 9's for that Comp XE268 224/230 cam... maybe even step back to an XE 262 or Summit 1103 cam...

12-18-2012 06:40 PM

cdminter59

Quote:

Originally Posted by txdude350

Okay, I like the idea of using lunati, I have heard good things. But my concern right now is compression.

Okay so I am trying to calculate all this and have come up with this below. I am not 100% sure am at TDC, and the deck clearance is measured with a 6" scale, but everything else should be pretty accurate. Getting frustrated here...

I just noticed the 70cc chambers so Cr. would be 8.96:1 with all the above specs. I wouldn't go any larger on cam Duration with that Cr. You would need to Mill the Heads or change the Pistons to raise the Cr. any higher.

I would also go with the Edelbrock Performer RPM intake #7101.

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